Magnetospheric Multiscale (MMS)

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What is MMS?

What questions are we answering with MMS?
  • MMS Narrated Orbit
    Scientist John Dorelli explains the MMS mission's orbit and why the four spacecraft fly in a tetrahedron formation.

    On its journey, MMS will observe a little-understood, but universal phenomenon called magnetic reconnection, responsible for dramatic re-shaping of the magnetic environment near Earth, often sending intense amounts of energy and fast-moving particles off in a new direction. Not only is this a fundamental physical process that occurs throughout the universe, it is also one of the drivers of space weather events at Earth. To truly understanding the process, requires four identical spacecraft to track how such reconnection events move across and through any given space in 3D.

  • NASA Administrator and Media to See MMS Mission Progress
    NASA Administrator Charles Bolden had a firsthand look at work being done on the Magnetospheric Multiscale (MMS) spacecraft during a visit to the agency's Goddard Space Flight Center in Greenbelt, Maryland, on Monday, May 12, 2014. Bolden visited Goddard's Integration and Test Facility where the four MMS spacecraft are undergoing testing. The spacecraft were in a rare four-stack arrangement inside a clean room after completing vibration testing. The clean room itself was temporarily altered to allow a close-up view of the approximate 20-foot high collection of four observatories in their launch configuration. In addition to Bolden, MMS project personnel were available to answer questions about the mission, ground testing and preps for launch. During its two-year mission, MMS will explore the mystery of how magnetic fields around Earth connect and disconnect, explosively releasing energy — a process known as magnetic reconnection. The four MMS spacecraft will provide the first three-dimensional views of this fundamental process that occurs throughout our universe.
  • MMS Mission Trailer
    In March 2015, NASA will launch four identical spacecraft to study how magnetic fields around Earth connect and disconnect, explosively releasing energy – a process known as magnetic reconnection. The Magnetospheric Multiscale, or MMS, mission will provide the first three-dimensional views of this fundamental process that can accelerate particles to nearly the speed of light. MMS uses Earth’s protective magnetic space environment, the magnetosphere, as a natural laboratory to directly measure reconnection. Reconnection is a common processes in our universe; occurring in space near Earth, in the atmosphere of the sun and other stars, in the vicinity of black holes and neutron stars, and at virtually any boundary between space plasmas, including the boundary between our solar system's heliosphere and interstellar space.

Science Results

  • MMS Sees a New Type of Reconnection
    The Magnetospheric Multiscale (MMS) mission consists of four identical satellites that traverse various regions of Earth's magnetosphere measuring the particles and electric and magnetic field which influence them. In the turbulent plasma between Earth's magnetopause and bow shock, a region called the magnetosheath, the MMS satellite constellation has measured multiple jets of energetic electrons between magnetic bubbles. This appears to be a new 'flavor' of magnetic reconnection based on electrons and occuring on smaller time and spatial scales than the standard model of magnetic reconnection with ions.
  • Zoom in to MMS and Magnetopause Reconnection
    This visualization starts with the viewer camera just outside earth's magnetosphere (the faint grey mesh) looking down on the orbit of the four MMS spacecraft. During this portion of the mission, the apogee of the orbit takes the spacecraft just outside the magnetopause. The lower orbit speed at this location maximizes the time spent there and increases chances of catching a reconnection event which is the goal of the mission.
  • Data Tour of MMS and Magnetopause Reconnection
    In this data visualization, we fly around with the MMS spacecraft in tetrahedral formation. The mesh structure in the distance is the magnetopause.
  • MMS First Results
    Like sending sensors up into a hurricane, NASA has flown four spacecraft through an invisible maelstrom in space, called magnetic reconnection. Magnetic reconnection is one of the prime drivers of space radiation and so it is a key factor in the quest to learn more about our space environment and protect our spacecraft and astronauts as we explore farther and farther from Earth.
  • Exploring Reconnection - Guide Field Off
    One of the aspects of magnetic reconnection which makes it a difficult process to fully understand is the complex interactions between charged particles and the electromagnetic fields that dominate their motion. The electromagnetic fields determine the motion of the particles, but the motion of the particles changes the configuration of the electromagnetic fields.
  • NASA Spacecraft Finds New Magnetic Process in Turbulent Space
    Though close to home, the space immediately around Earth is full of hidden secrets and invisible processes. In a new discovery reported in the journal Nature, scientists working with NASA’s Magnetospheric Multiscale spacecraft — MMS — have uncovered a new type of magnetic event in our near-Earth environment by using an innovative technique to squeeze extra information out of the data.

Magnetic Reconnection

  • Several NASA Spacecraft Track Energy Through Space
    Taking advantage of an unprecedented alignment of eight satellites through the vast magnetic environment that surrounds Earth in space, including NASA's ARTEMIS and THEMIS, scientists now have comprehensive details of the energy's journey through a process that forms the aurora, called a substorm. Their results showed that small events unfolding over the course of a millisecond can result in energy flows that last up to half an hour and cover an area 10 times larger than Earth.

    Trying to understand how gigantic explosions on the sun can create space weather effects involves tracking energy from the original event all the way to Earth. It's not unlike keeping tabs on a character in a play with many costume changes, because the energy changes form frequently along its journey: magnetic energy causes eruptions that lead to kinetic energy as particles hurtle away, or thermal energy as the particles heat up. Near Earth, the energy can change through all these various forms once again.

    Most of the large and small features of substorms take place largely in the portion of Earth's magnetic environment called the magnetotail. Earth sits inside a large magnetic bubble called the magnetosphere. As Earth orbits around the sun, the solar wind from the sun streams past the bubble, stretching it outward into a teardrop. The magnetotail is the long point of the teardrop trailing out to more than 1 million miles on the night side of Earth. The moon orbits Earth much closer, some 240,000 miles away, crossing in and out of the magnetotail.

  • Reconnection Fronts - What the Models Say...
    Mathematical models of Earth's magnetosphere have become increasingly more complex and accurate. They have sufficient detail to illustrate many small-scale phenomena. In this simulation run of the Geospace General Circulation Model (GGCM) we see new details that have been observed by in situ satellites. As the solar wind is deflected around Earth's magnetosphere (the 'bubble' of plasma surrounding Earth held by Earth's magnetic field), plasma flows within the bubble can change. In the graphics below, physical variables such as magnetic field and electric currents are plotted. With these variables, we overlay the net flow of the plasma (arrows), subjected to selection criteria to separate flows of plasma away from Earth and towards Earth. Green arrows are low-speed flows (below about 150 kilometers/second), while red arrows correspond to high-speed plasmal flows (about 300 kilometers/second and higher).
  • Space Weather
    This movie takes us on a space weather journey from the center of the sun to solar eruptions in the sun's atmosphere all the way to the effects of that activity near Earth. The view starts in the core of the sun where atoms fuse together to create light and energy. Next we travel toward the sun's surface, watching loops of magnetic fields rise up to break through the sun's atmosphere, the corona. In the corona is where we witness giant bursts of radiation and energy known as solar flares, as well as gigantic eruptions of solar material called coronal mass ejections or CMEs. The movie follows one of these CME's toward Earth where it impacts and compresses Earth's own protective magnetic bubble, the magnetosphere. As energy and particles from the sun funnel along magnetic field lines near Earth, they ultimately produce aurora at Earth's poles.
  • Magnetic Reconnection 2
    This is an update to an older magnetic reconnection animation (10072). The ionized wind from the Sun generates reconnection in the Earth's magnetic field. Particles leak in from the rediation belts producing the auroras.
  • IMAGE and Cluster View Magnetic Reconnection
    The IMAGE and Cluster spacecraft were ideally positioned in their orbits to view the reconnection event which led to the proton aurora formation.
  • Reconnection: Solar Wind Breaches the Earth's Magnetic Shield
    The Far Ultraviolet camera aboard the IMAGE spacecraft captured this view of a proton aurora (the bright spot near the center of the view) as well as the ring of the electron aurora. The protons for this aurora came from the incoming solar wind. They made it though the Earth's magnetic shield in a magnetic reconnection event higher in the magnetosphere which was detected by the Cluster satellite. Note: A 'corner' appears in the data in the beginning as the IMAGE spacecraft moves into a position where it can view the entire north polar region.
  • Reconnection at the Sun
    Two NASA spacecraft have provided the most comprehensive movie ever of a mysterious process at the heart of all explosions on the sun: magnetic reconnection.

    Magnetic reconnection happens when magnetic field lines come together, break apart, and then exchange partners, snapping into new positions and releasing a jolt of magnetic energy. This process lies at the heart of giant explosions on the sun such as solar flares and coronal mass ejections, which can fling radiation and particles across the solar system.

    Magnetic field lines, themselves, are invisible, but the sun's charged plasma particles course along their length. Space telescopes can see that material appearing as bright lines looping and arcing through the sun’s atmosphere, and so map out the presence of magnetic field lines.

    Looking at a series of images from the Solar Dynamics Observatory (SDO), scientists saw two bundles of field lines move toward each other, meet briefly to form what appeared to be an “X” and then shoot apart with one set of lines and its attendant particles leaping into space and one set falling back down onto the sun.

    To confirm what they were seeing, the scientists turned to a second NASA spacecraft, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). RHESSI collects spectrograms, a kind of data that can show where exceptionally hot material is present in any given event on the sun. RHESSI showed hot pockets of solar material forming above and below the reconnection point, an established signature of such an event. By combining the SDO and RHESSI data, the scientists were able to describe the process of what they were seeing, largely confirming previous models and theories, while revealing new, three-dimensional aspects of the process.

  • Magnetic Reconnection Throughout the Solar System
    Magnetic reconnection is one of the most important processes in the space. Reconnection occurs when crossed magnetic field lines snap, explosively flinging away nearby particles at high speeds. The following animations illustrate this magnetic explosion on the Sun, near black holes, around Earth.

MMS Orbit Configurations

Spacecraft Animations

  • MMS Launch & Deploy (Narrated)
    In March of 2015, an unprecedented NASA mission will launch to study a process so mysterious that no one has ever directly measured it in action. To create the first-ever 3-dimensional maps of this process, a process called magnetic reconnection, which occurs all over the universe, the Magnetospheric Multiscale, or MMS, mission uses four separate spacecraft equipped with ultra high speed instruments.

    Launching four satellites into space simultaneously is a complicated process. In addition, each spacecraft has six booms that will unfold and extend in space once in orbit. A launch and deployment with so many moving parts must be meticulously planned.

    Watch the video to get a sneak preview of how MMS will make this journey: The four spacecraft are housed in a single rocket on their trip into space. One by one, each ejects out, before moving into a giant pyramid-shaped configuration. Next each spacecraft deploys its six booms.

    Once in orbit, MMS will fly through regions near Earth where this little-understood process of magnetic reconnection occurs. Magnetic reconnection happens in thin layers just miles thick, but can tap into enough power at times to create gigantic explosions many times the size of Earth.

    Reconnection happens when magnetic field lines explosively realign and release massive bursts of energy, while hurling particles out at nearly the speed of light in all directions. Magnetic reconnection powers eruptions on the sun and – closer to home – triggers the flow of material and energy from interplanetary space into near-Earth space. The MMS orbit will carry the four spacecraft through reconnection regions near Earth, using this nearby natural laboratory to better understand how reconnection occurs everywhere in space.

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  • MMS Spacecraft Animation
    The Magnetospheric Multiscale (MMS) mission is a Solar Terrestrial Probes mission comprising four identically instrumented spacecraft that will use Earth’s magnetosphere as a laboratory to study the microphysics of three fundamental plasma processes: magnetic reconnection, energetic particle acceleration, and turbulence. These processes occur in all astrophysical plasma systems but can be studied in situ only in our solar system and most efficiently only in Earth’s magnetosphere, where they control the dynamics of the geospace environment and play an important role in the processes known as “space weather.”

    Learn more about MMS at

  • MMS Launch and Deployment
    This animation follows Magnetosphere Multiscale(MMS) Mission from launch at Kennedy Space Center through deployment and on station doing science. The MMS mission is comprising four identically instrumented spacecraft that will use Earth’s magnetosphere as a laboratory to study the microphysics of three fundamental plasma processes: magnetic reconnection, energetic particle acceleration, and turbulence.
  • MMS & Front-Side Reconnection
    This animation show the MMS spacecraft transiting through a reconnection event on the front side of Earth.


  • Stacking the spacecraft
    The Magnetospheric Multiscale, or MMS, mission stacked all four of its spacecraft in preparation for vibration testing. This time lapse shows one image every thirty seconds over three days of work. First, the spacecraft are assembled into mini-stacks, or placed on top of each other in sets of two. To create a full stack, engineers lift one mini-stack on top of another. Vibration testing simulates the conditions that the MMS spacecraft will experience during launch. MMS will study how the sun and the Earth's magnetic fields connect and disconnect, an explosive process that can accelerate particles through space to nearly the speed of light. This process is called magnetic reconnection and can occur throughout all space.
  • MMS: Engineering Challenges
    It's hard enough to build one spacecraft, but the Magnetospheric Multiscale Mission (MMS) is building four. Together, the spacecraft will unlock the mysteries of magnetic reconnection, when magnetic fields explosively connect and disconnect, transferring energy.
  • MMS Spin Test
    The four MMS observatories each undergo what's called a spin test, to learn how well the spacecraft is balanced. Italso provides information on how well the mass properties of an observatory can be measured and aligned. This movie shows Observatory #4 undergoing the test in May 2013 on the MRC Mark V spin balance machine. After launch, the MMS observatories will spin at approximately 3 revolutions per minute during normal operations.

Pre-Launch Videos